Resettlement process may have substantial impact on those seeking asylum

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Refugees granted asylum in Sweden were 66% more likely to develop schizophrenia or another nonaffective psychotic disorder than nonrefugee migrants from the same regions.

Note that the study suggests that increased risk of nonaffective psychotic disorders among immigrants may be due to a higher frequency of exposure to social adversity before migration, including the effects of war, violence, or persecution, although further studies will be needed.

Refugees granted asylum in Sweden were 66% more likely to develop schizophrenia or another nonaffective psychotic disorder than nonrefugee migrants from the same regions, a cohort study revealed.

The increased risk of psychosis was more pronounced in men (P=0.001), was about three times more likely to occur in refugees than in native-born Swedes (adjusted HR 2.9, 95% CI 2.3-3.6), and about twice as likely to occur in refugees than in nonrefugee migrants (HR 1.7, 95% CI 1.3-2.1), according to Anna-Clara Hollander, PhD, of the Karolinska Institute in Stockholm, and colleagues.

All refugees were at increased risk of psychosis regardless of where they came from, the investigators reported online in The BMJ. The exception was sub-Saharan Africa, where both refugees and nonrefugee migrants had high rates of psychosis relative to the Swedish-born population (HR 5.23, 95% CI 4.32-6.34).

"Our study shows that, on average, refugees in a high-income setting face substantially elevated rates of schizophrenia and other non-affective psychoses, in addition to the array of other mental, physical, and social inequalities that already disproportionately affect these vulnerable populations," they wrote.

"Our findings are consistent with the hypothesis that increased risk of non-affective psychotic disorders among immigrants is due to a higher frequency of exposure to social adversity before migration, including the effects of war, violence, or persecution. Further studies will be needed to confirm this possibility."

There is already substantial evidence that the risk of nonaffective psychosis is increased by a factor of 2.5 in migrants, Cornelius Katona, MD, medical director of the Helen Bamber Foundation in London, wrote in an accompanying editorial.

"In my view, however, there are also more fundamental lessons to be learned," Katona wrote. The resettlement process may further increase risk of mental illness in an already vulnerable population exposed to a "prolonged and distressing process" that may include institutional detention, loss of meaningful work, destitution, and poor access to health and social support, Katona said.

The study lacked information on post-migration risk factors such as racism and discrimination, he noted, a limitation acknowledged by the investigators.

In addition to questions about the validity of current diagnostic systems, cultural and linguistic barriers "may further impede definitive diagnosis," said Katona, who pointed to evidence linking the occurrence of psychotic symptoms in those with a primary diagnosis of post-traumatic stress disorder (PTSD). There may also be a significant overlap in genetic vulnerability to schizophrenia and to PTSD as evidenced in studies of U.S. veterans.

"The clinical challenges facing mental health professionals working with refugees and asylum seekers should not be underestimated," Katona wrote. "Diagnostic uncertainties should not, however, result in under-detection and under-treatment of serious mental health problems in this vulnerable group."

For the study, investigators extracted data from Psychiatry Sweden, a longitudinal database of official residents dating back to 1932. Cohort participants were older than 14 years and had a diagnosis of nonaffective psychotic disorder between Jan. 1, 1998 and Dec. 31, 2011.

A total of 1,347,790 people were included in the study. In all, 88.4% were people born in Sweden to two Swedish-born parents, 1.8% were refugees, and 9.8% were nonrefugee migrants from the Middle East and north Africa, sub-Saharan Africa, Asia, Eastern Europe, and Russia.

Cox regression analysis was used to estimate adjusted hazard ratios for nonaffective psychotic disorders by refugee status and region of origin, controlling for age at risk, sex, disposable income, and population density.

During 8.9 million person-years of follow-up, 3,704 cases of nonaffective psychotic disorder were identified. The study revealed that the crude incidence rate of nonaffective psychotic disorders was:

38.5 (95% CI 37.2-39.9) per 100,000 person-years in the Swedish-born population

"The potential effect of a fair and responsive asylum system on mental health outcomes in general and incidence of non-affective psychosis in particular remains to be determined," Katona wrote. "Meanwhile, however, a robust mental health response to the refugee 'crisis' must lie in a combination of clinical vigilance, recognition of vulnerability factors, and, above all, a determination to minimize the aggravating effects of post-migration experiences."

Funding for this study was provided by FORTE, the Wellcome Trust, the Royal Society and the Swedish Research Council.

No conflicts of interest were disclosed.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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